Still pressing the case for intensified warfare against Britain, Admiral Raeder persuaded Hitler to mount Luftwaffe mass bombing raids on the British seaports of Portsmouth, Bristol, Liverpool, and the Firth of Clyde. In preparation for this heavy assault, to take place between March 10 and 20, Luftwaffe planners demanded detailed U-boat weather reporting between those dates. When this demand reached Dönitz on March 9, he had only four U-boats in the North Atlantic and one of them, U-95, had no torpedoes. He assigned a Germany-bound boat, Clausen in U-37, to a “north” weather station and Schreiber in U-95 to a “south” weather station. That left only two boats to wage the North Atlantic convoy war: Otto Kretschmer’s U-99 and a brand-new VIIC, U-74, commanded by Eitel-Friedrich Kentrat, age thirty-four, from the duck U-8. It was a “fantastic situation,” Dönitz complained in his diary.
But reinforcements were on the way. On March 11 Fritz-Julius Lemp sailed from Germany in the new IXB U-110, manned by many seasoned Veterans of Lemp’s U-30. Lemp had been absent from the Atlantic for six months; the U-110 had been caught temporarily in Baltic ice and as a result, the boat had had only ten days of crew training “in freezing weather” and no torpedo, gunnery, or pack attack drills. The next day Joachim Schepke, the second-ranking tonnage ace after Kretschmer, sailed in U-100, having enjoyed ten weeks of home leave, vacation, and publicity tours. The ice in home waters had also prevented Schepke from conducting refresher drills.
While Lemp and Schepke were rounding the British Isles, the Luftwaffe commenced its devastating mass bombing raids on British seaports, and the big German surface ships in the Atlantic were on the move. Sailing far to the west into Canadian waters (near Newfoundland Bank) on March 15 and 16, the battle cruisers Gneisenau and Scharnhorst again attacked dispersing outbound convoys, sinking sixteen merchant ships for 82,000 tons, then headed for Brest. The heavy cruiser Hipper sailed from Brest on March 15 to join the “pocket” battleship Admiral Scheer for a break back to Germany through the Denmark Strait. Getting wind of some of these movements, the Admiralty deployed heavy units from the Home Fleet and from Halifax to intercept the ships, but the Germans cleverly eluded the pursuers.
Three days after reaching the Atlantic, on the afternoon of March 15, Lemp in U-110 took up a position about 150 miles south of Iceland. Since the visibility was very poor, he submerged every four hours to listen on hydrophones for convoy propeller noises. At 10:00 that night, the sonar operator reported the heavy, slow thump-thump-thump of distant propellers. Lemp surfaced and ran down the bearing. He saw “15-to-20 steamers” and “several large tankers” and “at least two destroyers.” At ten minutes past midnight, March 16, Lemp got off a contact report to Dönitz and prepared to attack.
This was convoy Halifax 112, composed of forty-one fully laden merchant ships and tankers. It was guarded by Escort Group (EG) 5, which had joined it that morning. Commanded by Donald Macintyre* in the World War I destroyer Walker, EG-5 was composed of four other old destroyers (Vanoc, Volunteer, Sardonyx, Scimitar) and two new corvettes (Bluebell, Hydrangea). Hastily formed in early March, EG-5 had sailed on its maiden voyage with an outbound convoy and was then on its homebound leg. It had had no tactical drills before sailing.
Lemp chose what he believed to be a 10,000-ton tanker for his first target. Actually, it was the 6,200-ton British tanker Erodona. He fired two bow torpedoes at her. The first broached and ran erratically; the second missed. A third torpedo from a stern tube hit, causing an immense explosion which led Lemp (and Donald Macintyre in Walker) to believe Erodona had been “blown to bits.” In reality, the ship was only severely damaged and it was later towed into Iceland.
The flames lit up the area “like daylight.” The destroyer Scimitar saw U-110 and charged, bringing up Walker and Vanoc, the latter equipped with a nonrotating Type 286M radar. Seeing the destroyers, Lemp dived and went deep under the convoy at high speed. The destroyers dropped twenty-four depth charges where he had dived, to no effect. Walker rejoined the convoy, leaving Vanoc and Scimitar to “hold down” the U-boat until the convoy was safely past—or so it was thought.
An hour later, Lemp surfaced and chased the convoy. At 0410 he sent Dönitz another report, then mounted a second attack. Having reloaded his tubes, Lemp fired four bow torpedoes, two at a freighter, two at a tanker. One broached; the other three missed. A fifth torpedo, he claimed, hit an 8,000-ton tanker, but that hit could not be confirmed. EG-5 was unaware of this second attack by U-110.
Lemp tracked doggedly during the early morning of March 16, broadcasting positions. When Dönitz ordered all boats in the vicinity to report their positions, he heard from the north weather boat, Clausen in U-37, Kretschmer in U-99, Schepke in U-100, and, surprisingly, Kentrat in U-74, who was under orders to relieve U-95 as the south weather boat. Dönitz ordered Lemp to send beacon signals for the benefit of the nearest boats, U-37 and U-99. Lemp did so, but then a mechanical problem and later a Sunderland forced him to run submerged and he lost contact. However, at noon Clausen in U-37 made contact and broadcast beacons which brought up Kretschmer’s U-99 and Schepke’s U-100.
At about sunset that evening, Lemp regained contact with the convoy and broadcast a position report and beacon signals. This brought in Kentrat’s U-74, but in the interim, Lemp lost contact again. When Kentrat came alongside to confer by megaphone, Lemp, believing the convoy had zigged sharply northeast, suggested both boats should search in that direction. This assumption took U-74 and U-110 off in the wrong direction. By then U-37, U-99, and U-100 had made contact, but none broadcast any beacon signals to help Lemp and Kentrat.
The three boats in contact with Halifax 112 closed to attack. The original alarm from Lemp had reported “at least two destroyers” in the escort, an estimate that had not been revised. Clausen, Schepke, and Kretschmer were therefore astonished to find not two but seven escorts—five destroyers and two corvettes. One of the destroyers, Scimitar, sighted Schepke in U-100 and drove him under, calling up the destroyers Walker and Vanoc. When Schepke came up an hour later, a destroyer was still present. It drove him down a second time and dropped depth charges.
Otto Kretschmer commenced his attack at about 10:00 P.M. He boldly steamed into the middle of the convoy on the surface and fired his eight remaining torpedoes. It was another remarkable performance by Kretschmer. One torpedo missed, but the other seven slammed into six different ships, four of them tankers, which exploded in searing flames. Kretschmer believed that all six ships, totaling 59,000 tons, had sunk, making this salvo the single most destructive of the war and, counting earlier sinkings, bringing his total bag on this patrol-to a record-setting 86,000 tons. But he had overestimated his latest sinkings by one vessel. Five ships, including three tankers* for 34,500 tons, sank, but the sixth, the 9,300-ton British tanker Franche Comte, got her fires under control and survived. Hiding in the dense smoke from the burning tankers and dodging the seven escorts, Kretschmer plotted a course to take him out of the area and on to Lorient.
The other boats, meanwhile, were attempting to attack. It was not an easy setup. The flames from the burning tankers brightly lit the area. The seven escorts swarmed hither and yon, adding more light with star shells and dropping depth charges. At fifty minutes after midnight, Donald Macintyre in Walker spotted a U-boat close ahead and put on full speed to ram. This was probably Clausen in U-37, who had not yet fired torpedoes. He crash-dived U-37 100 yards ahead of Walker. Macintyre ran right over the boat and dropped ten depth charges set for 250 feet. He heard a “heavy explosion” and saw “orange flames” in his wake and believed he had sunk his first U-boat. But he had not. Clausen in U-37 reported heavy collision damage which forced him to resume his voyage to Germany.
Headed off in the wrong direction, Lemp in U-110 and Kentrat in U-74 saw the flames and explosions. They turned about and ran full speed toward the battle scene. Coming up, both saw escorts everywhere firing star shells and dropping depth charges. Nonplussed by the sight of all these escorts—many more than he had reported—Lemp logged that the convoy “must have been reinforced” by other destroyers. Both boats had narrow escapes with destroyers; neither could get in.
Macintyre in Walker got a “firm” sonar contact at 0130, March 17. This was Schepke in U-100, who had not yet fired any torpedoes either. Macintyre called up the destroyer Vanoc and let loose a salvo of nine depth charges, set for 500 feet. When the noise subsided, Macintyre regained contact and fired off eight more depth charges with deep settings. Vanoc arrived, gained contact, and almost immediately fired six depth charges, set for 150, 250, and 500 feet. Walker then went off to rescue some survivors, but Vanoc continued the hunt. After she regained sonar contact, Vanoc fired six more depth charges with the same settings.
Some of these twenty-nine depth charges fell very close to U-100. The explosions smashed instruments, knocked out the pumps, and caused heavy flooding. The boat went out of control and slid, stern first, to 750 feet—deeper than any U-boat had ever gone. Fearing that the pressure hull might implode, and believing that he could torpedo Vanoc, Schepke ordered the engineer to blow all ballast tanks and surface.
Schepke came up at about 0300. By then Walker had rejoined Vanoc. The technicians manning the Type 286M radar on Vanoc picked up a contact at 1,000 yards—the first verifiable British surface-ship radar contact on a U-boat. At about the same time, Schepke saw Vanoc, which was coming on at full speed to ram. To back the boat around and fire torpedoes, Schepke called for full power, but the diesels wouldn’t start, nor, at first, the electric motors. When the motors finally came on the line, Schepke mistakenly ordered full speed ahead, rather than astern, on the starboard motor, ruining any chance of firing torpedoes.
Schepke thought Vanoc would miss astern, but he was wrong. Killing her engines to minimize damage to herself, Vanoc hit the U-100 at a perfect right angle on the conning tower at 0318. Schepke shouted “Abandon ship!” They were his last words. Vanoc’s huge sharp bow crushed him to death on the bridge. The U-100 sank almost immediately. Vanoc signaled Walker: “Have rammed and sunk U-boat.”
After picking up thirty-eight survivors of the freighter J. B. White, sunk by Kretschmer, Walker rushed up to circle Vanoc protectively while Vance’s men fished survivors of U-100 from the water. Vanoc found six, including Siegfried Flister, who was making an indoctrination cruise with Schepke before taking command of his own boat, and five enlisted men.
Close by, Kretschmer in U-99, was still trying to slip out of the area undetected and go home. His onetime quartermaster, Heinrich Petersen, for whom Kretschmer had obtained a Ritterkreuz and who had been promoted to lieutenant and second watch officer, had the bridge watch. One lookout was not alert. Glancing into the lookout’s zone, Petersen saw Walker merely a few yards off. Believing that U-99 must have been seen, Petersen made a serious mistake and ordered a crash dive, rather than running off in darkness at full speed.
No one on Walker had seen U-99, but while Walker was still circling Vanoc, the sonar operator picked up a contact. Macintyre disbelieved the report—a third U-boat contact in as many hours was simply too much to credit—but when the operator insisted it was a moving U-boat, Macintyre ordered an attack. Walker ran down the bearing and dropped six depth charges at U-99, which was trying to run off at about 400 feet. The charges exploded close beneath the boat, tossing it wildly and smashing air, fuel, and ballast tanks. Flooding and out of control, the U-99 slid down to 700 feet or more. Realizing the boat could not survive submerged, Kretschmer blew all ballast tanks and the U-99 shot to the surface. Kretschmer had no torpedoes; he hoped to escape in darkness.
Nine minutes after Walker dropped her depth charges, at 0352, Vanoc signaled Walker: “U-boat surfaced astern of me.” Vanoc beamed her searchlight on U-99 and both ships opened fire with 4” guns. Kretschmer called for full power, but neither the diesels nor electric motors would function. Moreover, the steering gear was broken. With a heavy heart, Kretschmer gave orders to scuttle and abandon ship. He got off a final, terse, confused, plain-language radio message to Dönitz: “Two destroyers. Depth charges. 53,000 tons. Capture. Kretschmer.” He then notified Walker with his signal light: “We are sunking [sic].” Walker and Vanoc ceased fire after two minutes, having registered no hits, and prepared to capture survivors.
Walker closed the flooding U-99 cautiously, with scramble-nets rigged. She picked up forty men, including the new, twenty-three-year-old first watch officer, Hans-Joachim von Knebel-Doberitz; the second watch officer, Ritterkreuz holder Heinrich Petersen; a prospective commanding officer, Horst Hesselbarth; two midshipmen on an indoctrination cruise; and, lastly, Kretschmer. The engineer, Gottfried Schroder, who had gone back to open ballast-tank vents—probably needlessly—and two enlisted men were not found.
At Kerneval, Dönitz first learned of the disaster from the crippled, Germany-bound U-37, which picked up and relayed Kretschmer’s final, confused message. It came as a shattering blow; doubly so as nothing had been heard from Prien in U-47 or Matz in U-70for ten days (since March 7) and all hope for them had been lost. Nor, ominously, was there any word from Schepke in U-100.
Winston Churchill helped clear the air. Even before Macintyre’s EG-5 reached Liverpool to great acclaim, he announced to the House of Commons that Germany’s two leading U-boat aces, Otto Kretschmer and Joachim Schepke, had been captured and killed, respectively. That announcement forced Berlin to concede the loss on March 20.* The communique sent a shock wave through the U-boat arm, for by then it was known that Prien had been lost as well.
British intelligence deduced from the POWs of U-70, U-99, and U-100 that Prien, too, was gone, and those sources played a role in the Admiralty’s decision to credit Wolverine with the kill. But the Admiralty did not rush to claim credit for killing Prien and U-47. Nor did Berlin have anything to say. Prien’s biographer, Wolfgang Frank, wrote that Hitler forbade the release of news of Prien’s loss, since it would “have a deleterious effect on the public morale,” especially if announced close to the loss of Kretschmer and Schepke. Berlin withheld the news of Prien’s loss, Frank wrote, for ten more weeks—to May 23.†